BAGHDAD: A column of 3,000 Shia militia fighters arrived at a military base near Ramadi on Monday as Baghdad moved to retake the western Iraqi city that has fallen to Islamic State militants in the biggest defeat for the government since mid-2014.

Setting the stage for renewed fighting over the city, Islamic State (IS) militants advanced in armoured vehicles from Ramadi towards the base where the Shia paramilitaries were massing for a counter-offensive, witnesses and a military officer said.

At the same time, US-led warplanes stepped up raids against IS fighters, conducting 19 strikes near Ramadi over the past 72 hours at the request of the Iraqi security forces, a coalition spokesman said.

The Shia militia, known as Hashid Shaabi or Popular Mobilisation, was ordered to mobilise after the city, the capital of Anbar province, was overrun on Sunday.

The militiamen give the government far more capability to launch a counterattack, but their arrival could add to sectarian animosity in one of the most violent parts of Iraq.

“Hashid Shaabi forces reached the Habbaniya base and are now on standby,” said the head of the Anbar provincial council, Sabah Karhout. They were fully equipped and highly capable, the council said.

An eyewitness described a long line of armoured vehicles and trucks mounted with machine guns and rockets, flying the yellow flags of Kataib Hezbollah, one of the militia factions, heading towards the base about 30 km (20 miles) from Ramadi.

Spokesmen for militia groups said reconnaissance and planning were underway for the upcoming “battle of Anbar”, the vast Euphrates River valley province where the US military fought the biggest battles of its 11-year occupation.

Ramadi is dominated by Sunni Muslims. Prime Minister Haider al-Abadi signed off on the deployment of Shia militias to attempt to seize back the area, a move he had previously resisted for fear of provoking a sectarian backlash.

About 500 people have been killed in the fighting for Ramadi in recent days and up to 8,000 have fled, a spokesman for the provincial governor said.

Islamic State said it had seized tanks and killed “dozens of apostates”, its description for members of the Iraqi security forces. An eyewitness in Ramadi said bodies of policemen and soldiers lay in almost every street, with burnt-out military vehicles nearby.

Harsh return to reality

The city's fall marked a major setback for the forces ranged against Islamic State: the US-led coalition and the Iraqi security forces, which have been propped up by Iranian-backed Shia militias. It was also a harsh return to reality for Washington, which at the weekend had mounted a special forces raid in Syria in which it said it killed an Islamic State leader in charge of the group's black market oil and gas sales, and captured his wife.

The Iraqi government and Shia paramilitaries recaptured Saddam Hussein's Tigris river home city of Tikrit from Islamic State six weeks ago, the biggest advance since the militants swept through northern Iraq last year. But government forces have had less success in the valley of Iraq's other great river, the Euphrates, west of Baghdad.

An army major who fought his way out of Ramadi said government forces in the area had been ordered to regroup, but soldiers were exhausted and morale was at rock bottom.

To some analysts, the fall of Ramadi shows the limits of the US strategy of attacking from the air but leaving ground fighting to Iraq's military and its Iran-backed militia allies.

“The Americans said that they have carried out air strikes against ISIS but then the group went in and defeated the local forces,” said Hassan Hassan, author of a book on Islamic State. “So they really need to come up with a whole new strategy... and really take the fight to them.” Qassim al Fahdawi, an Iraqi government minister, said Iraqi forces lacked the professionalism, training and discipline to withstand a smaller number of skilled Islamic State fighters.

While the government in Baghdad has urged Sunni tribes in Anbar to accept help from Shia militia against Islamic State, many Sunnis view the Shia militiamen as a worse threat than the jihadists. Islamic State portrays itself as a defender of Sunnis against sectarian attacks by the Iran-backed fighters.

One Anbar Sunni tribal leader now in exile in the Kurdish regional capital Erbil said the deployment of the Hashid Shaabi into the Sunni stronghold showed that Baghdad's goal was to crush Sunnis.

“They wanted to destroy this citadel and break its walls so that the Hashid could enter in order to spread Shi'ism,” Sheikh Ali Hamad said.

But some Anbar tribes are so fearful of Islamic State's harsh rule that they may be open to a role even for the hated Shia militias. Another tribal leader, Sheikh Abu Majid al-Zoyan, said he was suspicious of the militias, but “at this stage, we welcome any force that will come and liberate us from the chokehold” of Islamic State.

Kerry confident

US Secretary of State John Kerry expressed confidence that the takeover of Ramadi would be reversed in the coming weeks.

Ali Akbar Velayati, a senior Iranian official, said Tehran was ready to help confront Islamic State, and he was certain the city would be “liberated”.

Islamic State, which emerged as an offshoot of Al Qaeda, controls large parts of Iraq and Syria in a self-proclaimed caliphate where it has carried out mass killings of members of religious minorities and beheaded hostages.

A senior Israeli intelligence official said that before coalition forces began operations against the group, its revenues were about $65 million a month, more than 90 percent of which came from oil and the rest from taxes and ransom money.

Since then, monthly revenues had fallen to about $20 million, of which about 70 percent is from oil and the rest from taxes and ransom.